Re: [gpsd-users] Enable PPS Echo

[Gary E. Miller]

Yo Reto!

On Tue, 5 Apr 2016 23:07:13 +0000
Reto Zbinden ST <address@hidden> wrote:

> As far as I can see in the log, GPSD is using KPPS, so we're fine
> with that:

Cool.

> From my understanding this PPS echo stuff doesn't really require any
> special GPS hardware. The feature should be provided by the PPS API
> and simply clears the RTS line of the serial port as soon as the PPS
> event is timestamped. For the serial port PPS echo should be
> available:

I have a pile of GPS here, and I have never seen RTS hooked up.  Hard enough
to get the vendors to hook up the PPS line.

Believe or not, someone at Skytraq just told me they could not hook
up PPS to theior USB chip since USB only had two signal wires.  :-(

> I've found some further explanations here:
> http://www.ntp.org/ntpfaq/NTP-s-config-tricks.htm#AEN4296

That only seems to work on the DCD line, not on CTS or RI...

That mentions the Garmin GPS 35.  The GPS 35 clearly has no RTS pin
connected:

http://static.garmin.com/pumac/GPS35LPSeries_TechnicalSpecification.pdf

So the loop must only be local to the serial port, not to the GPS and back.

> But with my rather basic (linux) knowledge, it isn't clear to me if
> and how echo can be enabled for the PPS device.

Well, your link shows no such thing.


RGDS
GARY
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Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        address@hidden  Tel:+1 541 382 8588

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